Which of the following statement(s)… - JEE Main 2026 Chemistry PYQ

JEE Main 2026 — Chemistry Physical Chemistry

2026mcqmedium

Which of the following statement(s) is/are true ?

A. If two orbitals have the same value of $(n + l)$ , the orbital with lower value of $n$ will have lower energy.

B. Energies of the orbitals in the same subshell increase with increase in atomic number.

C. The size of $2p_x$ orbital is less than the size of $3p_x$ orbital.

D. Among $5f$ , $6s$ , $4d$ , $5p$ and $5d$ orbitals, none of the orbitals have $2$ radial nodes.

Choose the correct answer from the options given below :

Official previous-year question

Held on 5 Apr 2026 · Verified 6 Jul 2026.

Options

A
A, B and C only
B
A and C only
C
C and D only
D
A only

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Solution

Statement A: According to the $(n+l)$ rule, if two orbitals have the same $(n+l)$ value, the orbital with the lower value of $n$ has lower energy. This statement is true.

Statement B: As the atomic number increases, the effective nuclear charge ( $Z_{eff}$ ) increases. The energy of an orbital is proportional to $-\dfrac{Z_{eff}^2}{n^2}$ . Thus, the energy becomes more negative, meaning the energy of the orbitals in the same subshell decreases with an increase in atomic number. This statement is false.

Statement C: The size of an orbital increases with an increase in the principal quantum number $n$ . Therefore, the size of the $2p_x$ orbital is less than the size of the $3p_x$ orbital. This statement is true.

Statement D: The number of radial nodes is given by the formula $n - l - 1$ .

For $5f$ : $5 - 3 - 1 = 1$

For $6s$ : $6 - 0 - 1 = 5$

For $4d$ : $4 - 2 - 1 = 1$

For $5p$ : $5 - 1 - 1 = 3$

For $5d$ : $5 - 2 - 1 = 2$

Since the $5d$ orbital has exactly $2$ radial nodes, the statement that none of the orbitals have $2$ radial nodes is false.

Therefore, only statements A and C are true.

Answer: A and C only

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